/*
 * Copyright (C) 2020 Graylog, Inc.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the Server Side Public License, version 1,
 * as published by MongoDB, Inc.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * Server Side Public License for more details.
 *
 * You should have received a copy of the Server Side Public License
 * along with this program. If not, see
 * <http://www.mongodb.com/licensing/server-side-public-license>.
 */
package org.graylog.plugins.views.search.engine.monitoring.data.histogram.creation;

import java.util.Collection;
import java.util.function.ToLongFunction;

public class MaxValueComputation<T> implements ValueComputation<T, Long> {

    private final ToLongFunction<T> valueRetrievalFunction;

    public MaxValueComputation(final ToLongFunction<T> valueRetrievalFunction) {
        this.valueRetrievalFunction = valueRetrievalFunction;
    }

    @Override
    public Long computeValue(final Collection<T> elementsInBin, final int totalElements) {
        return elementsInBin.stream()
                .mapToLong(valueRetrievalFunction)
                .max()
                .orElse(0L);
    }
}
